Nusantara Day is an official Indonesian observance held on December 13 every year. It commemorates the adoption of the Djuanda Declaration of 1957, which made Indonesia the world’s first archipelagic state.

Nusantara is an Old Javanese world that literally means “archipelago”. In the Middle Ages, the concept of Nusantara was applied to the territory of the Majapahit Empire. Today, Nusantara is a term for the Indonesian archipelago (the national territory of Indonesia).

Indonesia is the largest island country in the world. It is made up of more than 17,000 islands, the largest being Java, Sumatra, Sulawesi, Borneo (shared with Malaysia and Brunei), and New Guinea (shared with Papua New Guinea). The concept of Indonesia’s special status as an archipelagic state was first formulated by Prime Minister of Indonesia Djuanda Kartawidjaja in the so-called Djuanda Declaration adopted on December 13, 1957.

According to the declaration, the waters enclosed by the straight baselines connecting the outermost points of the outermost Indonesian islands are internal waters subject to the country’s sovereignty. The baselines formed Indonesia into a single unified territory (Nusantara) for the first time in the history of independent Indonesia.

The principles of the Nusantara were officially recognized in the United Nations Convention on the Law of the Sea that was signed in 1982 and came into force in 1994.